C habits to give up

C++ is a flexible language. You can write C++ that a C compiler could compile. You can even write in a style that isn't too distant from Fortran 77. But if you're a C programmer who wants to make the most of modern C++, the following points are worth bearing in mind

• Think in terms of objects rather than functions. Groups of objects are easier to organise (using inheritance) than are groups of functions.
• Use namespaces: functions can have shorter names; information hiding is easier; and it's easier to switch between different implementations. Use namespace rather than files to control scoping.
• Use references rather than pointers when you can.
• Use strings. You can convert between C and C++ strings

    char cstring[]="a test"; 
    string a_str;
    a_str=string(cstring);
    strcpy(cstring, a_str.c_str());
  

• Don't use NULL - use 0
• Create variables just before first use. In particular, create for loop index variables within the loop construction.
• Use exceptions when the code that has to deal with a problem is far from the code that discovers the problem.
• Use const as much as possible. Note that in C++, const variables have internal linkage by default whereas in C, they have external linkage.
• Use enum
• Don't use type-identifer fields in structures
• Avoid pre-processor macros. const, inline, template and namespace replace most of #define usage, leading to stronger typing and better control of scope. For example

  const int answer = 42;
  template<class T> inline T min(T a, T b) {return (a<b)?a:b;}
  

• Avoid static except within functions.

  // better than a global
  int & use_count()
  {
  static int uc =0;
  return uc;
  }
  

  or use nameless namespaces

  namespace {
  class X{};
  void f(); // like a static
  int i;
  }